Hello, my name is Karl Ziemelis, and I am the Chief Physical Sciences Editor for Nature.

　　大家好，我是Karl Ziemelis（卡尔 泽梅里斯），《自然》物理科学的总编。 

　　It is my pleasure today to introduce a new paper that we are publishing in Nature: the title is “Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources”.  

　　非常荣幸今天来为大家介绍即将发表在《自然》上的这篇论文：“Ultrahigh-energy photons up to 1.4 petaelectronvolts from 12 γ-ray Galactic sources”。 

　　But first, let me give you a bit of background. 

　　首先我想向大家介绍一些研究背景。 

　　Cosmic rays are what we call the charged particles flying around the Universe at velocities approaching the speed of light. This is so fast that, for some of them, their energies can reach colossal values - more than 100 times greater than can be achieved for particles accelerated by researchers here on Earth – at the Large Hadron Collider, for example.  

　　宇宙射线是一些带电粒子，在宇宙中以接近光速的速度飞行。它们的速度如此之快，以至于其中一些粒子所携带的能量十分巨大，例如，比地球上的科学家在大型强子对撞机上加速粒子所能达到的能量值还要高出100倍以上。 

　　We have a name for the powerful cosmic accelerators responsible for these extremely energetic cosmic rays – we call them PeVatrons. Where and what they are remains an open question, but this new paper provides some important clues. 

　　我们为这种驱动宇宙粒子加速从而成为蕴含极大能量宇宙射线的天体起了一个名字，拍电子伏特宇宙线加速器，即PeVatron。它们在哪里，它们是什么，我们依旧没有答案，但这篇论文为我们提供了一些重要的线索。 

　　Tracing the origin of these high-energy cosmic rays is not a straightforward task, as magnetic fields in space can cause their paths to twist and bend when they travel: so when we detect such a cosmic ray arriving at the earth, we may be able to determine the direction it arrived from, but this is not necessarily the same direction it started from. 

　　追踪这些高能量宇宙射线并非易事，因为太空中的磁场会让粒子的行进路线扭曲、弯折，所以当侦测到有这样的射线抵达地球时，我们或许可以确定它到达的方向，但这个方向却未必与其出发方向一致。 

　　But we do know that cosmic rays should produce γ-rays close to their accelerators, so maybe in searching instead for the sources of high-energy γ-rays could pinpoint the locations of these mysterious PeVatrons 

　　不过，我们已知宇宙射线在其加速器附近会产生γ射线，所以或许寻找这种高能γ射线可以为寻找这些神秘的PeVatron指明方向。 

　　This is what Zhen Cao and colleagues have done in the new paper. They report the detection of 12 sources of ultrahigh-energy γ-ray photons, each of which represents a potential PeVatron in the Milky Way galaxy. Although the precise location of most of these sources remains unclear, the authors do firmly identify one candidate in the well-known supernova remnant known as the Crab Nebula. 

　　这就是曹臻和同事们在这个新研究中所做的工作。他们报告了检测到的12个超高能γ射线光子源，其中的每一个都代表着银河系中一个潜在的PeVatron。尽管这些光子源中大部分尚未找到准确位置，但作者确认了其中一个就位于著名的超新星遗迹蟹状星云中。 

　　These exciting findings, while still preliminary, were made possible by observations from one of the arrays of the partially completed Large High-Altitude Air Shower Observatory in China. Many more of these sources are expected to be found once this instrument is complete.  

　　这些激动人心的发现尽管还很初步，但却是因为部分建成的中国高海拔宇宙线观测站的观测工作才成为可能。未来待观测站全部完工后，相信还会发现更多这样的光子源。 

　　But what we can say for sure is that PeVatrons do exist in the Milky Way, and these findings bring us closer to understanding the origins of extremely high energy cosmic rays.  

　　不过我们已经可以肯定银河系中存在PeVatron，这些发现让我们离了解高能宇宙射线起源又近了一步。 

　　Thank you 

　　谢谢大家！